Gas hydraulic spring for crushing apparatus



- April 25, 1967 H. C. POLLITZ- 3,315,902

GAS HYDRAULIC SPRING FOR CRUSHING APPARATUS Original Filed Aug. 31, 1962 INVENTOR. HAROLD 6. POL L/TZ W QM ATTORNEY United States Patent Claims. Cl. 241-231 This application is a division of copending application Ser. No. 220,697, filed August 31, 1962, now abandoned, of the same title.

The present invention concerns rock crushers of the roll type which incorporate spaced crushing members between which rock is crushed by movement of the members with respect to each other, and particularly relates to means for maintaining and adjusting the spacing between the members and for permitting it resiliently to increase should the design load of the crusher be exceeded.

Roll type crushers customarily incorporate coil spring assemblies compressed both to maintain spacing between the rolls and partially to absorb overloads. Owing to the fact that otherwise extremely large diameter spring material with its consequent high internal stresses would have to be employed, the only practicable sized coil springs that can be utilized in these assemblies require compression through a substantial distance before sufficient force can be exerted thereby; .in fact, each such assembly generally requires a pair or more of such springs and compression of the latter is usually accomplished by turning up several large screw nuts. Adjustment of the crusher, therefore, requires both substantial time and effort to turn up the nuts one by one until proper force is exerted. by the springs. Furthermore, the nuts must be fully backed off in order to permit the insertion or removal of the shims, customarily used to fix the minimum spacing between the crushing rolls, each time the spacing between the rolls is altered and then laboriously retightened.

In roll type crushers the fact that the springs must be compressed to such an extent in order to achieve suflicient loading results in little remaining compression being available before the springs bind. Thus, means must usually be provided in order to prevent overloads should the springs be compressed so far that their coils bind. Devices for this purpose are well-known in the art and, for instance, deliberately permit fracture of an easily replaceable part. Such a device is shown, as applied for example to a roll type crusher, in US. Patent 2,273,772 to Pollitz. Though such devices avoid damage to the crusher they nevertheless require that operation of the crusher cease until the fractured part can be removed, a replacement installed, and the crusher readjusted. This in turn requires that the whole lengthy process of first turning off and then retightening the compressing nuts be undertaken, which also adds to the shutdown time.

' In the typical roll crusher, in which the journal boxes at each end of one of the crushing rolls are movable rela' tive to the journal boxes of the other roll in order to adjust the spacing between the rolls, the desired spacing being achieved usually by means of shims interposed between the journal boxes at the corresponding ends of each roll, one or more hydraulic springs of the present invention are simply mounted between the frame and the journal box at each end of the movable roll in place of the usual coil spring assemblies. Each hydraulic spring incorporates essentially a hydraulic cylinder pressurized with a suitable gas which in turn exerts its force upon a main piston and a piston rod. An additional or floating piston may also be incorporated in the cylinder rod to provide for better lubrication and sealing. Snub bolts are pro- 3,315,902 Patented Apr. 25, 1967 vided in the frame and can be turned up against one end of each spring. Each unit is pressurized so that the total of the forces exerted by all such springs is preferably equal to the design load of the crusher. As used herein the expression design load of the crusher is intended to refer to the load above which damage to the crusher begins to be likely. The design load is thus greater than what may be called the crushing or working load which is that imposed upon the crusher during its regular crushing operation. Accordingly, should an overload occur, that is, when the design load of the crusher would be exceeded, the gas in the cylinders is simply compressed, allowing the spacing between the rolls resiliently to increase and then to return to its original setting after discharge of the extraneous matter. Furthermore, the use of these springs also eliminates the need for overload safety devices, such as illustrated in the aforesaid patent, and consequent shutdown of the crusher should overload occur. The latter is compensated for instead simply by providing a sufficient stroke for the piston of each hydraulic spring.

Finally, in a roll crusher employing the present invention the laborious and lengthy process of turning up or undoing several screw nuts is unnecessary in order to achieve the necessary spring pressure. lnstead, such pressure is instantly available as soon as the snub bolts are turned up to capture the hydraulic springs firmly between the frame and the movable journal boxes of a roll crusher. Note also that the snub bolts need not be turned up to compress the gas, but only enough to remove any play between the ends of each spring and the seats against which they abut. This is of particular advantage inasmuch as presently the screw nuts of each spring assembly must be backed off completely each time shims are to be added or removed in order to alter the spacing between the rolls and then retightened. Each hydraulic spring can be simply and easily installed or removed inasmuch as it is not only wholly self-contained but also has a fixed, maximum length; it is not necessary, therefore, to discharge the cylinder in order to release the spring from the crusher or to adjust the spacing between the crushing members.

Accordingly, the primary object of the present invention is the provision of a self-contained gas hydraulic spring for rock crushers of the type described which permits both the spacing between the crushing members to be easily and quickly adjusted and an overload to be safely absorbed without need of crusher shutdown.

Another object of the present invention is to provide crushers of the type described with self-contained gas hydraulic springs interposed to resist increase in the spacing between the crushing members, each spring incorporating a cylinder filled with gas to a pressure so that the total force exerted by all such cylinders is equal to the design load of the crusher.

A further object of the present invention is the provision of crushers of the kind described with gas hydraulic springs interposed to resist increase in the spacing between the crushing members, each spring incorporating a piston, a piston rod and a cylinder filled with gas to a pressure so that the total force exerted upon all the piston rods is equal to the design load of the crusher, each spring being self-contained and having a fixed maximum length.

An additional object of the present invention is to provide a selfcontained gas hydraulic spring of fixed maximum or minimum length for crushers of the kind described, each unit incorporating a cylinder, a main piston and piston rod and a floating piston, the cylinder being capable of being pressurized with gas betweenone end thereof and the free piston and of being filled with a noncompressible lubricating fluid between the main and floating pistons.

Other and further objects, features and advantages of the present invention will be apparent from the preferred form thereof hereinafter described, read in conjunction with the following drawings, in which:

FIGURE 1 is an elevational of one end of a typical roll type crusher illustrating the application of the present invention thereto; and

FIGURE 2 is a side view, partly in section, through the axis of one of the gas hydraulic springs utilized in the crusher illustrated in FIGURE 1.

The roll type crusher illustrated in FIGURE 1 incorporates a frame of any suitable construction upon which are mounted a pair of conventional crushing rolls 11 and 12 journaled at their respective ends in twopairs of journal boxes 13 and 14, respectively, each pair being horizontally spaced from the other atop frame 10. Journal boxes 14 are fixed to frame 10 and for this purpose the latter includes a pair of horizontally extending beams 15 and 1-6 transversely of each end of rolls 11 and 12 and vertically spaced from each other by means of columns 17 and 18 between their respective ends. Spacer blocks 19 are also interposed between the two journal boxes 13 and 14 at each end of the crusher and the entire assembly is tied together, with journal boxes 14 clamped tightly between beams 15 and 16, by means of suitable tie bolts 20. The opposed, horizontal faces of beams 15 and 16 between columns 17 and blocks 19 are provided with longitudinally extending ways along which journal boxes 13 are slidable in order to permit appropriate spacing between rolls 11 and 12, such spacing being determined by shims 21 interposed between journal boxes 13 and blocks 19. Any suitable means (not shown) may be employed to drive rolls 11 and 12 in opposite directions, as indicated by the arrows A and B in FIGURE 1, and an appropriate feed hopper 22 is mounted thereabove.

Between the opposed vertical faces of each respective pair of journal boxes 13 and columns 17 are secured a pair of gas hydraulic springs horizontally positioned one above the other. Inasmuch as each spring is identical with the other, only one need be described and is shown in detail in FIGURE 2 as incorporating a hollow cylinder 31, closed at one end by end cap '32, and provided with a main piston 33 slidable therein having a piston rod 34 integral therewith extending axially therefrom to beyond the other end of cylinder 31, an O ring 35 providing sealing between cylinder 31 and piston 33. The length of cylinder 31 and the stroke of piston 34 will, of course, depend primarily upon the amount of movement required of journal boxes 13 in order for the crusher safely to absorb any possible overload. The remaining end of cylinder 31 is internally threaded to receive an externally threaded end plug 36 bored axially to slidably receive piston rod 34 therethrough. An annular wiper type of seal 37 between rod '34 and plug 36 is provided at the outer end of the bore through the latter. End plug 36 is locked in place by means of a threaded retaining ring 38 turned up tightly thereagainst. Pison 33 and rod 34 are bored axially to provide a passage 39, communicating with the interior of cylinder 31', its outer end being counterbored in turn to receive a removable plug 40 threaded therein well below the outer end of rod 34. A second or floating piston 41 is also provided in cylinder 31 and is slidable therein between end cap 32 and piston 33. Piston 41 has its opposite ends 42, 42' dished and is equipped with an annular, axially extending relief 43 in its outer circumferential wall communicating with the space between pistons 33 and 41 by means of an inclined passageway 44. Sealing between cylinder 31 and piston 41 is accomplished by suitable 0 rings 45 received in a pair of axially spaced circumferential grooves straddling relief 43. Finally, the wall of cylinder 31 is bored between end cap 32 and piston 41 and provided with a suitable gas charging valve 46.

Before mounting each pair of hydraulic springs 30, plugs 40 are removed and the space between pistons 33 and 41 filled through passage 39 with a non-compressible fluid, such as heavy oil. Plugs 40 are then replaced and each pair of springs 30 is placed with their end caps 32 butted against one journal box 13, so that the resultant of their action is in a line through the axes of rolls 11 and 12 at one pair of corresponding ends thereof and parallel to the ways on which journal boxes 13 slide. While in this position a suitable gas, such as nitrogen, is then introduced through valves 46, forcing pistons 33 against end plugs 36, until the pressure in each cylinder 31 between end cap 32 and piston 41 is such that the sum of the forces on each piston 41, and thus on piston rods 34, is equal to the design load of the crusher. Finally, a pair of snub bolts 47, threaded horizontally through columns 17 from the outer face thereof, are turned up against the outer ends of piston rods 34, the latter being partially received in counter bores into the opposite face of columns 17 and the intermediate exposed portions of rods 34 being protected against grit and weather by appropriate boots 48 of neoprene, for instance. Since during normal operation of the crusher pistons 33 are hard against end plug 36, the gas exerts no pressure upon snub bolts 47. Thus, by simply backing off the latter a turn or two, each spring 30 can be easily and quickly removed as a self-contained unit. Similarly, if the spacing between rolls 11 and 12 is to be adjusted, an outward turn or two of snub bolts 47 permits shims to be added or subtracted between corresponding journal boxes 13 and 14, any alteration in the distance between the former and columns 17 being easily and quickly compensated for by adjustment of snub bolts 47. Should an overload occur, it will be transmitted through journal boxes 13 to cylinders 31, resiliently moving the latter in turn axially along piston rods 34 and compressing the gas between end caps 32 and pistons 41. When the extraneous matter has been discharged, the gas pressure will return journal boxes 13 to their original positions against shims 21.

The number of spring 30 employed at each end of roll 11 depends upon the capacity of the crusher. One may suflice in the case of those of smaller capacity, but in the case of those of larger capacity a pair of springs 30' are used in order that each cylinder 31 may be of convenient size. If a single cylinder were used in such case it would have to be of much larger diameter, in which instance it would occupy too much lateral space, or if of smaller diameter unfeasible gas pressures would be required. While it is not absolutely necessary to employ a floating piston 41 and oil or other incompressible fluid between it and piston 33, it is preferable, however, to do so in order to provide lubrication and better sealing for piston 33 than might otherwise be obtained without substantially more complexity. Relief 43 and its connecting passageway 44 permits the oil to contact the wall of cylinder 31 between O rings 45 and thus afford increased lubrication for piston 41 in addition to better sealing between the oil and the gas.

It will be appreciated, of course, that the present invention is also readily applicable to roll crushers in which both rolls are movable relative to the crusher frame. Indeed, an obvious design change in springs 30, inserting piston 41 slidably on piston rod 34 between piston 33 and end plug 36 and injecting the gas between the latter and piston 41, will permit them to resist tension, instead of compression, and thus allow them to be interposed, for instance, between the journal boxes at corresponding ends of a roll crusher. In the latter case springs 30 would have a fixed minimum, instead of a fixed maximum, over-all length.

While the present invention has been described with reference to particular embodiments and detailed descriptive language has been used, it is not so limited. Instead the following claims are to be read as encompassing all modifications and adaptations of the invention falling within the spirit and scope thereof.

I claim:

1. In a crushing device of the roll type having a frame and a pair of spaced crushing elements journaled at each of their axial ends for rotation on said frame adapted to crush material therebetween by rotation of said elements with respect to each other, at least one of said elements being movable with respect to the other in order to adjust the spacing therebetween, the combination therewith of gas hydraulic means for maintaining a predetermined spacing between said elements during their crushing operation up to a predetermined load and thereafter to accommodate an overload by resiliently increasing said spacing, said means comprising at least one piston housing having opposite ends at least one of which is closed, a piston in said housing slidable between said ends, and a compressible fluid under pressure between said piston and said closed end, one of said means being operatively associated with each journal of said movable element so that thrust between said elements is communicated to said housing and piston against the pressure of said fluid, the pressure in each of said housings being such that the total force exerted by all of said means is sufficient to maintain said predetermined spacing between said elements up to said predetermined load only, said means for one of said journals having no fluid connection with the means for the other of said journals during operation of said crusher, and means for adjusting the spacing between said elements, said adjusting means being effective independently of said fluid in said housing.

2. In a crushing device of the roll type having a frame and a pair of spaced crushing elements journaled at each of their axial ends for rotation on said frame adapted to crush material therebetween by rotation of said elements with respect to each other, at least one of said elements being movable with respect to the other in order to adjust the spacing therebetween, the combination therewith of gas hydraulic means for maintaining a predetermined spacing between said elements during their crushing operation up to a predetermined load and thereafter to accommodate an overload by resiliently increasing said spacing, said means comprising at least one cylinder closed at at least one of its two ends, a piston slidably mounted in said cylinder between said ends, and a compressible fluid under pressure between said piston and said closed end, one of said means being operatively associated with each journal of said movable element so that thrust between said elements is communicated to said cylinder and piston against the pressure of said fluid, the pressure in each of said cylinders being such that the total force exerted by all of said means is suflicient to maintain said predetermined spacing between said elements up to said predetermined load only, there being no expulsion of said fluid from said cylinder when said predetermined load is exceeded, and means for adjusting the spacing between said elements, said adjusting means being effective independently of said fluid in said cylinder.

3. In a crushing device of the roll type having a frame and a pair of spaced crushing elements journaled at each of their axial ends for rotation on said frame adapted to crush material therebetween by rotation of said elements with respect to each other, at least one of said elements being movable with respect to the other in order to adjust the spacing therebetween, the combination therewith of gas hydraulic means for maintain-ing a predetermined spacing between said elements during their crushing operation up to a predetermined load and thereafter to accommodate an overload by resiliently increasing said spacing, said means comprising at least one cylinder closed at at least one of its two ends, a piston slidably mounted in said cylinder between said ends, and a compressible fluid under pressure between said piston and said closed end, one of said means being operatively associated with each journal of said movable element so that thrust between said elements is communicated to said cylinder and piston against the pressure of said fluid, each of said means being self-contained and removable from said crusher without need to discharge any of said fluid therefrom, the pressure in each of said cylinders being such that the total force exerted by all of said means is sufiicient to maintain said predetermined spacing between said elements up to said predetermined load only.

4. In a roll crusher having a frame and a pair of spaced crushing rolls positioned thereon and rotatable with respect to each other to crush material therebetween, said rolls being journaled in bearings at each of their ends, the journals and bearings of one roll being fixed relative to said frame and the other journals and bearings of the other roll being movable in said frame in order to adjust the spacing between said rolls, the combination therewith of means operatively associated with the bearings at each end of said movable roll and said frame for maintaining a predetermined spacing between said rolls during their crushing operation up to a predetermined load therebetween and thereafter to accommodate an overload by resiliently increasing the spacing between said rolls, each of said means including at least one self-contained gas hydraulic spring assembly secured to said crusher comprising a cylinder closed at at least one of its two ends, a main piston slidably mounted in said cylinder between said ends and having a piston rod operatively connected thereto and extending outside of said cylinder through one of said ends, and a compressible fluid under pressure between said piston and said closed cylinder end, said means for one of said movable bearings having no fluid connection with the means for the other of said movable bearings during operation of said crusher, each of said means being disposed so that each of said spring assemblies thereof receives thrust between the bearings and said frame arising from the crushing operation axially of said assembly and against the pressure of said fluid therein, the pressure in each of said assemblies being such that the sum of the forces exerted by all of said assemblies is sufficient to maintain said predetermined spacing between said rolls only as long as the crushing load therebetween does not exceed said predetermined load, and means for adjusting the spacing between said rolls, said adjusting means being effective independently of said fluid in said cylinders.

5. The device of claim 4 wherein each bearing of said movable roll is slidable in a rectilinear path on said frame, and wherein one of said means is interposed directly between said frame and each of said bearings of said movable roll, the resultant of the forces exertable by said spring assemblies thereof extending through and being perpendicular to both axes of said rolls at their corresponding ends, the cylinder end remote from. said first closed end also being closed and said piston rod extending through said remote closed end, said fluid being located between said first closed end and said. piston whereby each of said spring assemblies has a fixed, maximum overall length. i

6. The device of claim 5 wherein said adjusting means are disposed in said frame and operative axially against one end of each of said spring assemblies, the other end of the latter being butted against one of said movable bearings, whereby adjustment of said means compensates for adjustment of the spacing between said rolls without disturbing the fluid in said spring assembly or altering said overall length thereof.

7. The device of claim 5 wherein said cylinder is provided with a floating piston interposed for slidable movement therein between said first closed end and said main piston, said compressible fluid being disposed between said first closed end and said floating piston and a lubricating, non-compressible fluid between said main and floating pistons.

8. The device of claim 7 wherein the peripheral wall of said floating piston is provided about its circumference with an axially extending recess in order to form with the inner peripheral wall of said cylinder a lubricant-containing annulus, said floating piston having a passage from said annulus to the lubricant containing space between said pistons.

s. In a roll crusher having a frame and a pair of spaced :rushing rolls journaled at their respective axial ends for rotation on said frame and adapted to crush material therebetween by rotation with respect to each other, one of said rolls being fixed in said frame and the other of said rolls being movable in said frame with respect to the first in order to adjust the spacing therebetween, the combination therewith of a pair of gas hydraulic means for maintaining a predetermined spacing between said rolls during their crushing operation up to a predetermined load and thereafter to accommodate an overload by resiliently increasing said spacing, each of said means comprising at least one cylinder closed at its two ends, a main piston slidably mounted in said cylinder between said ends and a piston rod extending outwardly through one of said closed ends, and a compressible fluid under pressure between said piston and the other of said closed ends, whereby each of said means normally has a fixed maximum overall length alterable only upon compression of said fluid by said pistons, said means being applied to each of the journals of said movable roll so that thrust between said journals is communicated to said frame against the pressure of said fluid, each of said means being self-contained so as to be both operable upon said journals and removable from said crusher independently of each other,

the pressure in each of said cylinders being such that the total force exerted by all of said means is sufiicient to maintain said predetermined spacing between said elements up to said predetermined load only.

10. The device of claim 9 wherein adjusting means separate from said hydraulic means and operative thereagainst are provided in order to accommodate said normally fixed length of said hydraulic means to variations in the distance between the journals of both of said rolls arising from adjustment of the spacing therebetween.

References Cited by the Examiner UNITED STATES PATENTS 574,273 12/1896 Roger 241-231 2,273,772 2/1942 Pollitz 241-32 2,479,759 8/1949 Merchant 241-231 2,856,035 10/1958 Rohacs. 2,873,763 2/1959 Mercier 92l82 X 3,099,406 5/1963 Kautz 24132 ROBERT C. RIORDON, Primary Examiner.

D. KELLY, Assistant Examiner. 

2. IN A CRUSHING DEVICE OF THE ROLL TYPE HAVING A FRAME AND A PAIR OF SPACED CRUSHING ELEMENTS JOURNALED AT EACH OF THEIR AXIAL ENDS FOR ROTATION ON SAID FRAME ADAPTED TO CRUSH MATERIAL THEREBETWEEN BY ROTATION OF SAID ELEMENTS WITH RESPECT TO EACH OTHER, AT LEAST ONE OF SAID ELEMENTS BEING MOVABLE WITH RESPECT TO THE OTHER IN ORDER TO ADJUST THE SPACING THEREBETWEEN, THE COMBINATION THEREWITH OF GAS HYDRAULIC MEANS FOR MAINTAINING A PREDETERMINED SPACING BETWEEN SAID ELEMENTS DURING THEIR CRUSHING OPERATION UP TO A PREDETERMINED LOAD AND THEREAFTER TO ACCOMMODATE AN OVERLOAD BY RESILIENTLY INCREASING SAID SPACING, SAID MEANS COMPRISING AT LEAST ONE CYLINDER CLOSED AT AT LEAST ONE OF ITS TWO ENDS, A PISTON SLIDABLY MOUNTED IN SAID CYLINDER BETWEEN SAID ENDS, AND A COMPRESSIBLE FLUID UNDER PRESSURE BETWEEN SAID PISTON AND SAID CLOSED END, ONE OF SAID MEANS BEING OPERATIVELY ASSOCIATED WITH EACH JOURNAL OF SAID MOVABLE ELEMENT SO THAT THRUST BETWEEN SAID ELEMENTS IS COMMUNICATED TO SAID CYLINDER AND PISTON AGAINST THE PRESSURE OF SAID FLUID, THE PRESSURE IN EACH OF SAID CYLINDERS BEING SUCH THAT THE TOTAL FORCE EXERTED BY ALL OF SAID MEANS IS SUFFICIENT TO MAINTAIN SAID PREDETERMINED SPACING BETWEEN SAID ELEMENTS UP TO SAID PREDETERMINED LOAD ONLY, THERE BEING NO EXPULSION OF SAID FLUID FROM SAID CYLINDER WHEN SAID PREDETERMINED LOAD IS EXCEEDED, AND MEANS FOR ADJUSTING THE SPACING BETWEEN SAID ELEMENTS, SAID ADJUSTING MEANS BEING EFFECTIVE INDEPENDENTLY OF SAID FLUID IN SAID CYLINDER. 